#include <Eigen/Dense>
#include <iostream>

using namespace std;
using namespace Eigen;

int
main()
{
	Eigen::MatrixXf m(2, 4);
	Eigen::VectorXf v(2);

	m << 1, 23, 6, 9, 3, 11, 7, 2;

	v << 2, 3;

	MatrixXf::Index index;
	// find nearest neighbour
	(m.colwise() - v).colwise().squaredNorm().minCoeff(&index);

	cout << "Nearest neighbour is column " << index << ":" << endl;
	cout << m.col(index) << endl;
}
